Subungual Bowen disease in a patient with epidermodysplasia verruciformis presenting clinically as longitudinal melanonychia.

Epidermodysplasia verruciformis (EV) is a rare autosomal-recessive condition associated with a predisposition to infection with specific types of human papillomaviruses. A spectrum of wart-like lesions on the face, dorsa of the hands, and legs are characteristic clinical findings. Lesions usually develop in early childhood, persist, and may eventuate in cutaneous squamous cell carcinoma, usually in sun-exposed areas. These lesions are locally destructive and sometimes metastasize. We present a case of a 34-year-old African American woman with EV with a 9-month history of a right index finger ungual longitudinal pigmented band and nail splitting. Biopsy showed hyperkeratotic and parakeratotic subungual epithelium with verrucous hyperplasia. The superficial keratinocytes showed koilocytic changes. In addition, there was extensive, focally full-thickness keratinocyte dysmaturation with variable nuclear atypia and numerous mitotic figures, without apparent invasion. An associated melanocytic hyperplasia (confirmed by Melan-A stain), composed of large, pigment-laden dendritic melanocytes, was present without appreciable atypia or pagetoid spread. The findings are of a squamous cell carcinoma in situ arising in association with EV with incidental melanocytic hyperplasia. To the best of our knowledge, this is first report of a subungual presentation of this condition with associated melanonychia.